Ethnic differences in hemodynamic responses to stress in hypertensive men and women
Department of Psychiatry and Behavioral Sciences, Duke University Medical Center, Durham, North Carolina 27710, USA. American Journal of Hypertension
(Impact Factor: 2.85).
07/1995; 8(6):552-7. DOI: 10.1016/0895-7061(95)00036-O
Hemodynamic response patterns to three laboratory stressors were compared in 63 mildly hypertensive black and white men and women. Ethnic groups were matched for age, body mass index, and casual blood pressures. Stressors included a mental arithmetic task, a simulated public speaking task, and a forehead cold pressor test. Blood pressure increases during the stressors were similar in the two ethnic groups. However, the pressor responses were mediated by greater vascular tone in black compared to white subjects. These differences persisted whether the hemodynamic response pattern was associated with an overall fall (speech task) or rise (cold pressor) in systemic vascular resistance. Gender differences in the hemodynamic basis of pressor responding were also observed. Women, compared to men, exhibited greater increases in heart rate and smaller vascular contributions to their blood pressure increases during stress. Ethnic and gender differences are discussed in terms of the neurohumoral mechanisms mediating the cardiovascular stress response. The findings are consistent with converging evidence suggesting that beta-adrenergic receptor down-regulation is characteristic of hypertension in whites, whereas heightened vascular alpha-receptor sensitivity or early vascular hypertrophy may be a feature of hypertension in blacks.
Available from: Harriet de Wit
- "The finding of a possible racial difference in response to stress is consistent with several other reports of race differences (Ahwal et al, 1997; Chong et al, 2008; Sherwood et al, 1995). There are several important limitations of this study. "
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ABSTRACT: Stress plays an important role in psychiatric disorders, and preclinical evidence indicates that the central endocannabinoid system modulates endocrine and neuronal responses to stress. This study aimed to investigate the effect of acute stress on circulating concentrations of endocannabinoids (eCBs) in healthy humans. A total of 71 adults participated in two sessions in which they were exposed to either a standardized psychosocial stress procedure (Trier Social Stress Test) or a control task. Blood samples for eCB and cortisol assays and cardiovascular and subjective measures were obtained before and at regular intervals after the tasks. Serum concentrations of the eCBs, N-arachidonylethanolamine (anandamide, AEA) and 2-arachidonoylglycerol (2-AG), as well as of the N-acylethanolamides (NAEs), N-palmitoylethanolamine (PEA) and N-oleoylethanolamine (OEA), and of the O-acylglycerol, 2-oleoylglycerol (2-OG), were determined. Compared with the control condition, stress increased serum concentrations of AEA and the other NAEs immediately after the stress period. Increases in PEA were positively correlated with increases in serum cortisol after stress. Furthermore, anxiety ratings at baseline were negatively correlated with baseline concentrations of AEA. The sex and menstrual cycle status of the subject affected the NAE responses to stress. Interestingly, subjects of Asian and African-American races exhibited different patterns of stress responses compared with the Caucasian subjects. These results indicate that stress increases circulating NAEs in healthy human volunteers. This finding supports a protective role for eCBs in anxiety. Further research is needed to elucidate the function of these lipid mediators, and to determine the mechanisms that regulate their appearance in the circulation.
Available from: Keith M Diaz
- "In contrast, cardiac output was a prominent contributor to ABPM measurements only in whites and not in African Americans . Moreover, when the hemodynamic responses were compared among racial group after three separate laboratory stressors, the pressor responses in African Americans were found to be mediated to a greater extent by vascular tone when compared to whites . In keeping with the role of peripheral vascular resistance as the key determinant of DBP, it therefore may be reasonable to hypothesize that the strong associations found for the measures of DBP and MAP variations, and not for the SBP variations in the present study, may be attributed to the greater contribution of systemic vascular resistance to BP regulation in African Americans as they are exposed to daily stressors in their natural environment. "
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ABSTRACT: We investigated the relationship between renal function, blood pressure variability (BPV), and nitric oxide (NO) in a group of African Americans with normal or mildly impaired renal function. 24-hour ambulatory blood pressure monitoring was performed, NO measured, and glomerular filtration rate (GFR) calculated in 38 African Americans. Participants were categorized as having normal (GFR > 90 mL/min per 1.73 m(2)) or mildly impaired (GFR 60-89 mL/min per 1.73 m(2)) renal function. Diastolic BPV was significantly lower in the mildly impaired renal function group. Regression analyses revealed a significant positive association between GFR and diastolic BPV for the entire study group. Plasma NO levels were significantly higher in the mildly impaired renal function group and negatively correlated with diastolic BPV. In conclusion, diastolic BPV was reduced in African Americans with mildly impaired renal function, which may be the result of increased NO production. These results conflict with previous findings in diseased and nonblack populations and could provide rationale for studying BPV early in the disease state when BP-buffering mechanisms are still preserved.
Available from: Leonida Compostella
- "Various factors can influence the autonomic nervous system (ANS) and its responses to the different stimuli used in the tests for autonomic evaluation. In the selection of the study groups, most of the previous studies did not take into considerations factors that modify the function of the ANS, such as differences in age,    gender,  race, presence of obesity,  physical activity, diabetes mellitus,  alcohol abuse,   cigarette smoking,  hypertension, coronary artery disease  and pharmacological interventions      or other medical conditions usually associated with abnormal cardiac ANS. In our study, all these factors have been excluded and the group of our patients matches with the group of controls as regards anthropometric and social characteristics that could influence the ANS. "
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ABSTRACT: HIV infection causes cardiac autonomic neuropathy (CAN); little is known about the relevance of CAN in sub-Sahara African patients, in spite of the highest prevalence of AIDS in that population. The authors assessed prevalence rates of CAN in HIV-positive treatment-naïve African patients and investigated the correlation between degree of immunodeficiency and CAN.
Thirty HIV-positive patients and 11 HIV-negative controls underwent a battery of cardiovascular autonomic function tests; the Ewing-Clarke score was calculated along with the stage of severity of CAN. The patients' immunological status was evaluated by CD4 T-lymphocytes counts.
During paced respiration of normal depth, the patients showed shorter baseline RR intervals (739.2+/-136.0 vs 846.2+/-88.7 ms; P<0.05), with an inverse correlation with CD4 counts, and lower heart rate variability (85.3+/-73.0 vs 123.0+/-46.2 ms; P<0.02). Although patients with lower CD4 counts tended to present blunted response to hand-grip and cold-face tests, no linear correlation was found between results of cardiovascular reflex tests and CD4 counts. Eight patients (27%) obtained borderline Ewing-Clarke scores; 9 patients resulted affected by early (6 pts, 20%) or intermediate (3 pts, 10%) stage of CAN.
Signs of HIV-related CAN are present in 30% of the African HIV+ patients observed, with no direct correlation to their immunological status. Based on the relevance of the problem and the presence of signs of CAN even in newly diagnosed and treatment-naïve patients, the authors suggest that all HIV-patients should be screened for the presence of the complication, in view of the possible serious events associated with it.
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